Endophytic fungi—Big player in plant-microbe symbiosis

Endophytic fungi are recognized as beneficial microorganisms that form symbiotic relationships with plants. These fungi enhance plant adaptability to biotic and abiotic stresses, promote plant growth through the secretion of phytohormones, and facilitate nutrient absorption, while in return, they derive nutritional benefits from their host plants. Such intricate and balanced associations hold significant promise for agriculture, particularly in improving yield stability and stress tolerance in economically important crops. Despite decades of research deepening our understanding of fungal-plant symbiosis, systematic syntheses of emerging discoveries remain scarce. This paper elucidates three key insights: (1) the historical progression of research on endophytic fungi, tracing the field from early descriptive ecology to modern molecular insights into symbiosis; (2) the molecular cross-talk underpinning symbiotic progression, from initial recognition to metabolic integration; and (3) the molecular mechanisms by which endophytic fungi confer growth promotion and disease resistance to their host plants. By bridging fundamental symbiosis mechanisms with their potential agricultural applications, we provide a conceptual framework for leveraging endophytic fungi as biocontrol agents in sustainable agriculture. • Endophytic fungi exhibit remarkable host diversity and global distribution, enabling widespread ecological interactions. • Endophytic fungi, crucial helpers for their hosts, aid in plants adapting to diverse stresses in the external environment. • Endophytic fungi establish symbiotic relationships with their hosts through a delicate and intricate process. • Endophytic fungi promote plant growth through enhanced nutrient uptake and metabolic rewards.